The purpose of the research proposal is to extend the large body of already available physiological and biochemical findings on the mode of action of mitomycin by a systematic chemical investigation of the mechanism of interaction of this antibiotic and the DNA molecule. The information obtained mainly by chemical methods will be utilized ultimately for setting up the critical model system in vitro for the reaction of the antibiotic with its target. It is hoped that we shall isolate and identify the products of this reaction, yielding the clue to the nature of the interaction between the mitomycins and DNA.